import React, { useRef } from 'react'

function Count(props) {
  // console.log(props);

  const selectNumberRef = useRef()

  /**
   * 加
   */
  const increment = () => {
    const { value } = selectNumberRef.current
    props.jia(value * 1)
  }

  /**
   * 减
   */
  const decrement = () => {
    const { value } = selectNumberRef.current
    props.jian(value * 1)
  }

  /**
   * 如果为奇数，则加
   */
  const incrementIfOdd = () => {
    const { value } = selectNumberRef.current
    if (props.count % 2 !== 0) {
      props.jia(value * 1)
    }
  }

  /**
   * 异步延迟加
   */
  const incrementIfAsync = () => {
    const { value } = selectNumberRef.current
    props.jiaAsync(value * 1, 500)
  }

  return (
    <div style={{ width: 500, margin: '0 auto' }}>
      <h1>当前求和为：{props.count}</h1>
      <select ref={selectNumberRef}>
        <option value='1'>1</option>
        <option value='2'>2</option>
        <option value='3'>3</option>
      </select>
      <button onClick={increment}>+</button>
      <button onClick={decrement}>-</button>
      <button onClick={incrementIfOdd}>当前求和为奇数再加</button>
      <button onClick={incrementIfAsync}>异步加</button>
    </div>
  )
}

export default Count
